This application claims the priority of Japanese Patent Application Nos. 9-22940 and 9-267533, the disclosures of which are expressly incorporated by reference herein.
The present invention relates to a method and a system for evaluating the image quality of holograms.
Generally, the evaluation of the image quality of holograms is accomplished visually. Thus, this evaluation was usually performed non-quantitatively often producing a wide dispersion due to differing perceptions of the observers, and conditions under which the observations were made.
Regarding optical parts such as a mirror and a lens, the distribution of intensity of a point image is observed to evaluate its modulation transfer functions (referred hereinafter to as MTF). In view of the fact that such known evaluation methods using MTF cannot be applied to the evaluation of hologram images, JP-A 4-286932 proposes a new evaluation method wherein a real image of a hologram is formed through a convex lens arranged on the side of a light source or diffracted light to operate and evaluate MTF.
However, the method disclosed in JP-A 4-286932 serves to measure a point spread function (PSF), so that it can evaluate MTF of holographic opticall elements which reflect two-dimensional images and serve as a combiner of a headup display. This method, however, cannot evaluate the three-dimensional image quality of holograms.
It is, therefore, an object of the present invention to provide a method and a system for evaluating not only the quality of holograms with two-dimensional recorded images, but the quality of holograms with three-dimensional recorded images.
One aspect of the present invention lies in providing a method of evaluating a hologram, comprising the steps of:
measuring spacial distributions of luminance of an image reconstructed from the hologram and an object recorded thereon; PA1 normalizing amplitudes of luminance per spacial frequency, which are obtained by Fourier transforms of said spacial distributions measured, respectively; and PA1 comparing the normalized amplitudes. PA1 measuring spacial distributions of luminance of an image reconstructed from the hologram and an object recorded thereon; PA1 normalizing amplitudes of luminance per spacial frequency, which are obtained by Fourier transforms of said spacial distributions measured, respectively; and PA1 obtaining a ratio between the normalized amplitudes. PA1 a source illuminating light to the hologram and an object recorded thereon; and PA1 a luminance meter movably arranged with respect to the hologram and said object, said luminance meter serving to measure luminances of an image reconstructed from the hologram and light reflected by said object.
Another aspect of the present invention lies in providing a method of evaluating a hologram, comprising the steps of:
Still another aspect of the present invention lies in providing a system for evaluating a hologram, comprising:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.